Unless multicast or broadcast functionality is supported broadcast services will not be spectrum efficient in WiMax. There is however interresting oportunities in combination with technologies as DVB-T / DVB-H which are low entry broadcast technologies. The downside opf DVB-T/H is the lack of streaming on demand capabilities. This could make WiMax and DVB-T/H an interresting combo in some markets.

Have you heard of a company called Nextwave? They are working on WiMAX/DVB-H technology and it seems the DVB-H/WiMAX interface is proprietary though. The company also have spectrum to deploy the solution in US, Canada and Germany.

WiMAX can provide very efficient triple play broadcasting for Mobiles.Nextwave® has announced a mobile TV platform based on the use of mobile WiMAX technology. The Mobile WiMAX technology platform is based on Multicast and Broadcast (MBS) feature of the Mobile WiMAX technology. The multicast service in mobile Wimax uses macro-diversity features to ensure that all mobiles are able to receive the multicast transmissions. Unlike a unicast transmission of mobile TV which needs capacity for every mobile using the service, a multicast service can be scaled up to thousands of users in the same spectrum. ( See chapter 16- Mobile Broadcasting Using WiMAX- a technology overview).When dedicated for multicast upto 45 TV channels can be supported in a 10 MHz bandwidth carrier.
Developers of Mobile WiMAX technology and equipment such as Huawei and Alcatel Lucent have already committed to use the Nextwave® technology in their mobile WiMAX products based on IEEE802.16e-2005.http://www.wimax-home.com